Molecular assembly of 3-mercaptopropinonic acid and guanidine acetic acid on silver nanoparticles for selective colorimetric detection of triazophos in water and food samples

Abstract

In this work, a novel colorimetric nanosensor was developed for the selective detection of triazophos in environmental water and food samples using bifunctionalized silver nanoparticles (Ag NPs) as a probe. The Ag NPs were bifunctionalized with 3-mercaptopropinonic acid (MPA) and guanidineacetic acid (GAA) and used as a colorimetric probe for the selective sensing of triazophos via hydrogen bonding. The addition of triazophos into the bifunctionalized Ag NPs solution triggers the aggregation of bifunctionalized Ag NPs, inducing a color change from yellow to dark orange, which yields a red-shift in the surface plasmon resonance (SPR) peak of GAA-MPA-Au NPs. Results showed that the absorbance ratio (A550/A400) was linear with the logarithm of triazophos concentration in the range of 0.5–500μM and the detection limit (3σ) obtained by UV–visible spectra were 0.10 and 0.08μM using Tris-HCl pH 5.0 and sodium acetate pH 10.0 with addition of NaCl (0.4mM). The sensitivity of method was improved ∼85-fold using 0.4mM of NaCl as an ionic strength. This method was successfully applied to detect triazophos in water (tap, canal and river) and food (rice and apple) samples.